Observing different quantum trajectories in cavity QED

The experimental observation of quantum jumps is an example of single open quantum systems that, when monitored, evolve in terms of stochastic trajectories conditioned on measurements results. Here we present a proposal that allows the experimental observation of a much larger class of quantum trajectories in cavity QED systems. In particular, our scheme allows for the monitoring of engineered thermal baths that are crucial for recent proposals for probing entanglement decay and also for entanglement protection. The scheme relies on the interaction of a three-level atom and a cavity mode that interchangeably play the roles of system and probe. If the atom is detected the evolution of the cavity fields follows quantum trajectories and vice-versa.Comment: 5 pages, 2 figure

Fine-scale mapping of High Nature Value farmlands: novel approaches to improve the management of rural biodiversity and ecosystem services

High Nature Value farmlands (HNVf) are defined as rural lands characterized by high levels of biodiversity and extensive farming practices. These farmlands are also known to provide important ecosystems services, such as food production, pollination, water purification and landscape recreation. Recently, this concept has been introduced in Rural Development Programmes related to biodiversity preservation in traditional agricultural landscapes. However, there are no specific rules concerning the practical use of the concept, particularly on the identification of potential HNVf areas at a local scale. However, this application becomes important for farmland biodiversity protection in the context of multi-scale agricultural development. We present a novel approach for HNVf mapping, which provides an improved local discrimination of farmlands according to their contribution for the conservation of rural biodiversity and ecosystem services. Our approach is based on a multi-criteria valuation of habitat types based on the national land cover map and agrarian censuses. It is onsidered applicable in other EU countries since comparable datasets are usually available. This methodology is also expected to provide the backbone of a standard, cost-effective methodology for HNVf monitoring, with an emphasis on the impacts of land use change on species, habitats and landscape function

Nitric Oxide Regulates Neurogenesis in the Hippocampus following Seizures

Hippocampal neurogenesis is changed by brain injury. When neuroinflammation accompanies injury, activation of resident microglial cells promotes the release of inflammatory cytokines and reactive oxygen/nitrogen species like nitric oxide (NO). In these conditions, NO promotes proliferation of neural stem cells (NSC) in the hippocampus. However, little is known about the role of NO in the survival and differentiation of newborn cells in the injured dentate gyrus. Here we investigated the role of NO following seizures in the regulation of proliferation, migration, differentiation, and survival of NSC in the hippocampus using the kainic acid (KA) induced seizuremouse model. We show that NO increased the proliferation of NSC and the number of neuroblasts following seizures but was detrimental to the survival of newborn neurons. NO was also required for the maintenance of long-term neuroinflammation. Taken together, our data show that NO positively contributes to the initial stages of neurogenesis following seizures but compromises survival of newborn neurons.Foundation for Science and Technology (FCT, Portugal); COMPETE; FEDER [PTDC/SAU-NEU/102612/2008, PTDC/NEU-OSD/0473/2012, PEst-C/SAU/LA0001/2013-2014, PEst-OE/EQB/LA0023/2013-2014]; FCT, Portugal [SFRH/BPD/78901/2011, SFRH/BD/77903/2011

Spin wave vortex from the scattering on Bloch point solitons

The interaction of a spin wave with a stationary Bloch point is studied. The topological non-trivial structure of the Bloch point manifests in the propagation of spin waves endowing them with a gauge potential that resembles the one associated with the interaction of a magnetic monopole and an electron. By pursuing this analogy, we are led to the conclusion that the scattering of spin waves and Bloch points is accompanied by the creation of a magnon vortex. Interference between such a vortex and a plane wave leads to dislocations in the interference pattern that can be measurable by means of magnon holography

Coupling between magnetic field and curvature in Heisenberg spins on surfaces with rotational symmetry

We study the nonlinear $\sigma$-model in an external magnetic field applied on curved surfaces with rotational symmetry. The Euler-Lagrange equations derived from the Hamiltonian yield the double sine-Gordon equation (DSG) provided the magnetic field is tuned with the curvature of the surface. A $2\pi$ skyrmion appears like a solution for this model and surface deformations are predicted at the sector where the spins point in the opposite direction to the magnetic field. We also study some specific examples by applying the model on three rotationally symmetric surfaces: the cylinder, the catenoid and the hyperboloid. The coupling between a magnetic field and the curvature of the substract is an interesting result and we believe that this issue may be relevant to be applied in condensed matter systems, e.g., superconductors, nematic liquid crystals, graphene and topological insulators.Comment: To be published in Physics Letters